Spark plug



' June 13, 1933. H. M. LITTLE ET AL SPARK PLUG Filed March ll. 1952 J auM i. /4 l// H//H// nl /lww f a w i Ins Patented June 13, l 19.33

UNI-TED STATES PATENT OFFICE HORACE I.. LITTLE EDGAR B. HOLMES, F DKNY,COLORADO, ASSIGNORS TO AHERIOAN GYRO OF DENVER., COLORADO, A CORPORATION0F COLORADO eraan PLUG Application led lai-ch 11, 1932. Serial No.598,164.

This invention relates to improvements in spark plugs of the typeemployed in connection with internal combustion engines.

It is the object of this invention to produce a spark plug of suchconstruction that it will give two sparks within thecombustion chamberand which will also be provided with a condenser element on which acharge is induced by the high potential current which has the effect ofincreasing the intensity of the sparks across the two spark gaps.

Another object of this invention 1s toproduct a spark plug of suchconstruction that it shall be provided with a detonating chamber locatedabove the spark gaps and which will function to produce an explosionthat will drive 'gas downwardly between the inner surface of the tubularmetal bod member and the outer surface of the insulating core so as tofree the parts from carbon.

The above and other objects that may become apparent as this descriptionproceeds are attained by means of a construction and an arrangement ofparts that will now be described in detail, and for this purposereference will be had to the accompanying drawing in which the preferredconstruction has been illustrated, and in which:

Fig..1 is a longitudinal section through a spark plug constructed inaccordance with this invention;

Fig. 2 is an end elevation of the same; and

Fig. 3 is a diagram showing the relationship of the two electrodes tothe condenser element.

In the drawing reference numeral 5 indicates a tubular metal body memberwhich is of the usual construction and is provided with a threadedsection 6 that engages in the threaded spark plug openings of theengine. The inner surface of the opening in body member 5 is providedwith an inclined shoulder 7 on which is supported a gasket 8. Theinsulating core 9 has a shoulder that rests on the gasket 8 and is alsoprovided with another shoulder 10 on which a gasket 11 is supported. Aclamping nut 12 is threadedly connected `with the inside of the openingin the body member as indicated by reference nu- 50 meral 13. Theclamping member 12 holds the insulating body member securely in place 1na manner quite obvious from the drawing. The insulating member isprovided with a downwardly extending ortion 14 of somewhat smallerdiameter t an the correspond` ing portlon of the opening in the bodymember. An electrode 15 extends through the insulating member from oneend to the other and is attached at its upper end to the cylindricalmember 16, whose outer surface is threaded as indicated by referencenumeral 17. Member 16 has an outwardly extending shoulder 18 and anupwardly extending threaded portion 19. Secured to the upper end of theinsulating member is a washer or ferrule 20 that is held in lace bymeans of the flange 18. A cement p ug 21 is provided below the lower endof member 15 and serves to hold the parts against accidental movementafter they have been assembled. A

threaded sleeve 22 is secured to the threaded plug 19 and serves as aterminal for the high tension wires.

.The lower end of the body member is provlded with two openings 23 inwhich are located the ends 24 of a U-shaped condenser element, whosebase portion is indicated by reference numeral 25. The ends 24 aresurrounded by a tube of dielectric material 26 and this is held in placeby means of cement .27. The ends 24 of the U-sha ed member being spacedfrom the inner sur ace of the opening by the dielectric 26 form acondenser by means of which a charge of electricity can be stored.

Referring now to Fig. 2, it will be seen that electrode 15 is spaced ashort distance from the base 25 of the condenser member so as to form aspark ga 28. Another electrode which has been in irated by referencenumeral 29 is secured in an opening 30 in the end of the tubular bodymember and isl in electrical contact with the body member. The lower endof electrode 29 is bent at right angles so as to form a projectingportion 31 and is normally spaced a short distance from the condenserelement so as to form a spark gap 32. By referring to Fig. 3 it will beseen that the condenser element is located between the two electrodes 15and 31 and is separated from each whereby spark gaps 28 and 32 4areformed. When the spark plug is in place, it

is connected by means of a, conductor 33 to the secondary coil 34 of atransformer whose '5f primary has been indicated by reference numeral35. The other end of the secondary is grounded at 36 and the electrode31 is also grounded through the engine in the usual manner. It is aparent from the inspection 1 of Fig. 3, that'w en the electrodes 15 and31 are subjected to a high potential difference, a charge will beinduced on the condenser and this charge will contain a considerablequantity of electricity and when the potential dlfu ference becomeslarge enough to break down the two spark gaps, the condenser will bedis'- charged, thereby producing a much more 1ntense spark than if thecondenser action were not present. Besides the condenser action,

9. the action of the two spark gaps in series also thereby gets theaccumulative eil'ect of bothA of these intensifying actions.

Attention is called to the fact that that portion of the wall of theopening in the body member which has been indicated by reference numeral37 is rusto-conical and that the corresponding portion of the outersurface of the insulating core, which has been indicated by referencenumeral 38 is concave and therefore an annular chamber 39 is formedbetween the two surfaces. This chamber becomes filled with inflammablegas during the compression stroke and when the char in the engine isignited, the pressure within the chamber 39 increases very rapidly andby the time the llame reaches this gas, it is in condition to detonate,thereby producing a veryl strong explosion that drives the gasdownwardly between the outer surface of the insulating core and theinner surface of the body member and tends to keep the walls free fromsoot and other accumulations.

From the above description it will be apparent that the spark pluo'shown and described is of a simple and substantial construction and sodesigned that there are 'two spark gaps in series which are both locatedwithin the combustion chamber of the engine and in addition to this themember which extends between the two electrodes 15 and 31 is soconnected with the body member that a condenser action resul'ts, theeffect of which is to greatly increase the quantity of electricitydischarge at each operation of the spark gap and therefore a much moreintense spark is produced than if a single spark were used or 1f 'twospark gaps were used without the addition of the condenser action.

Having .described the invention what is claimed as new is:

A spark (plug comprising, in combination, a tubular bo y member, anelongated core of insulating material y extending through the same, anelectrode extendin through the core in the direction of its len andterminating beyond the inner end o the body member, the inner end of thebody member having two substantially parallel spaced openings extendingthereinto, a U-shaped condenser ele,- ment having its ends extendinginto the openings, the endsof the condenser element being surrounded bdielectric material which serve s to space t em from the sides of theopenings and to secure them to the body member, the condenser elementbeing spaced a short distance from 'the electrode to form a spark gap,and an electrode electrically connected with the 4body member and spaceda short distance from the condenser element, whereby when the twoelectrodes are sub- Jected to a difference of potential, the condenserelement will receive an induced charge and whereby when the differenceof potential between the two electrodes reaches a iven value, the twospark gaps will be broken own and two s arks produced.

In testimony whereof we aix our signatures.

HORACE M. LITTLE. EDGAR R. HOLMES.

